1. Field of the Invention
The present invention relates to a memory element and a method for making the memory element and, more particularly, to a resistance random access memory element and a method for making the resistance random access memory element.
2. Description of the Related Art
Memories have been widely used and are necessary in various electronic products. Great attention has been put in research and development related to memories. Due to the advantages of high operating speeds, low power consumption, fewer limitation to miniature processing, and storage of multi-bit, resistance random access memories have the potential to replace non-volatile floating gate memories as the non-volatile memory elements of the next generation.
With reference to FIG. 1, a conventional resistance random access memory element generally includes a first electrode 91, a second electrode 92, and an insulating layer 93 coupled between the first and second electrodes 91 and 92. Voltage is applied to the first and second electrodes 91 and 92 to form a plurality of current conduction paths 94, generating resistance switching characteristics for use as a memory.
Since transition metal oxides generate resistance switching characteristics easily, the insulating layer 93 of a resistive non-volatile memory is usually made of a transition metal oxide in current researches. However, due to incompatibility between the transition metal oxides and current semiconductor manufacturing processes, the resistance random access memories made of transition metal oxides must be made by processes other than those for semiconductors, resulting in high manufacturing costs. Furthermore, still referring to FIG. 1, the insulating layer 93 is generally made of uniform material without structural flaws, the current conduction paths 94 randomly extend from the first electrode 91 towards the second electrode 92. The lengths and routes of the current conduction paths 94 are not fixed, such that the resistance changes every time the voltage is switched, resulting in unstable resistance.
On the other hand, although the manufacturing costs can be cut if the insulating layer 93 is made of an oxide, nitride, or nitrogen oxide of a semiconductor that is compatible with current semiconductor manufacturing processes, the resistance switching characteristics can not be easily generated in the semiconductor material. To obtain the resistance switching characteristics in the semiconductor material, the insulating layer 93 must have a thickness of 1-100 nm, or additional processes are required to dope metal into the semiconductor material or to diffuse metal into the semiconductor material at high temperature.
Furthermore, the disadvantages of unstable lengths and unstable routes of the current conduction paths 94 still exist. As a result, the resistance after switching is unstable.
Thus, a need exists for a novel resistance random access memory element and a method for making the resistance random access memory element.